Sophisticated electronic gear, such as computers and communication equipment, requires highly effective shielding from various types of electromagnetic radiation. Electromagnetic radiation which can interfere with the operation of such equipment, or damage it, includes radio frequency interference (RFI), electromagnetic interference (EMI) and even ultraviolet. Another type of damaging electromagnetic phenomena is the so-called electromagnetic pulse, or EMP. This is a very damaging form of electromagnetic radiation which occurs in the immediate aftermath of a nuclear explosion. Protection from EMP is of particular interest in military applications.
Stationary and mobile guided missile installations, for example, require a great deal of computer and electronic communications equipment. Such equipment has been mounted on large vehicular trailers which carry bulkheads, a roof, and other structure for forming a closed operations chamber or room. It is necessary that such operations rooms be heavily shielded from radiation of the types discussed above.
These mobile operations rooms obviously must be provided with access doors. Such doors must also be heavily shielded, to block out undesirable electromagnetic radiation. Doors made of radiation-impervious materials, such as heavy steel and lead, are commonly used. These doors are hung, from a casing surrounding the door opening, on heavy hinges. The door is pivoted about a substantially vertical axis near one of its vertical edges.
Bulkhead doors are also employed in ships, airplanes and railroad trains. In some of these applications, such doors must provide the shielding explained above.
Such bulkhead doors must not leak appreciable radiation around their edges or elsewhere. If a good seal is not effected, leakage will result. Leakage will also result if the heavy door does not close straight into its opening, but rather becomes wedged at a slight angle.
Problems have also arisen from leakage through resilient sealing members which are employed to assist in providing an airtight seal around the doors. Such seating members are elastomeric and radiation pervious.
Since such bulkhead doors are often very large and heavy, it is desirable that locking mechanisms employed with the doors be simple and reliable in operation, and that they can be operated between locked and unlocked states by a single operator. It is also desirable that the locking mechanism provide for securing the door at multiple locations about its periphery, to enhance the uniformity and tightness of the seal.
Openings in the door surface provided for accepting handles have also caused leakage problems.
In some of the prior art bulkhead doors, the operator must provide a strong push on the door at the same time that he actuates the locking mechanism. This is necessary to move the door into its casing to some degree against the resilient sealing members before the door can be locked.
It is an object of the present invention to provide apparatus and method for easily locking a large radiation impervious bulkhead door against electromagnetic radiation, and for providing a uniform seal about the entire periphery of the door, without the need for large operator force being applied to compress the door seal.